JP2015184888A - display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the effect of a fictions touch "ghost" in touch detection.SOLUTION: A display device includes (a) detecting the presence or absence of noise or adhesion of a water droplet on the basis of currents flowing in a plurality of detection electrodes when a touch panel scanning voltage is supplied to the counter electrode of each of an m number of separate blocks; and (b) assuming that an (m+1) number of counter electrodes are present for the counter electrode of each of the m number of separate blocks, also assuming that a touch panel scanning voltage is supplied, which is synchronized with a touch panel scanning voltage supplied to the counter electrode of each of the m number of blocks, for the (m+1) number of the counter electrodes, and determining on the basis of currents flowing in the detection electrodes whether the presence is noise or a water droplet.

Description

  The present disclosure relates to a display device, and is applicable to, for example, an in-cell display device with a built-in touch panel.

A display device provided with a device (hereinafter also referred to as a touch sensor or a touch panel) for inputting information by performing a touch operation (contact pressing operation, hereinafter simply referred to as touch) using a user's finger or pen on a display screen. It is used in mobile electronic devices such as PDAs and portable terminals, various home appliances, and automated teller machines.
As such a touch panel, a capacitive system that detects a change in capacitance of a touched portion is known.
As this capacitive touch panel, a liquid crystal display device having a so-called in-cell type liquid crystal display device in which a touch panel function is built in a liquid crystal display panel is known (Japanese Patent Laid-Open No. 2009-258182).
In an in-cell type liquid crystal display device, a scanning electrode of a touch panel is used by dividing a counter electrode (also referred to as a common electrode) formed on a first substrate (so-called TFT substrate) constituting the liquid crystal display panel.

JP 2009-258182 A

It is necessary to avoid erroneous detection of electrostatic capacitance (foreign touch detection) in touch detection based on the result of electrostatic capacitance detection by detecting erroneous capacitance due to noise, water droplets, or other foreign matter. It is.
An object of the present disclosure is to provide a technique capable of reducing the influence of an imaginary touch “ghost” in touch detection in a display device incorporating a touch panel function.
Other problems and novel features will become apparent from the description of the present disclosure and the accompanying drawings.

The outline of a representative one of the present disclosure will be briefly described as follows.
That is, the display device includes a first substrate having a pixel electrode and a counter electrode, a second substrate having a plurality of touch panel detection electrodes, and a liquid crystal sandwiched between the first substrate and the second substrate. A driving circuit that supplies a counter voltage and a touch panel scanning voltage to the counter electrode, and a detection circuit that detects the presence / absence of a touch based on currents flowing through the plurality of detection electrodes. When m is an integer of 2 or more (m ≧ 2), the counter electrode is divided into m blocks. The counter electrode of each of the m divided blocks is provided in common for each pixel of a plurality of continuous display lines. The counter electrode of each block divided into m pieces also serves as the scanning electrode of the touch panel. The driving circuit sequentially supplies a touch panel scanning voltage to the counter electrode of each of the m divided blocks. (A) When a touch panel scanning voltage is supplied to the counter electrode of each of the m divided blocks, the detection circuit is configured to prevent noise or water droplets from being attached based on a current flowing through the plurality of detection electrodes. (B) It is assumed that the (m + 1) th counter electrode exists with respect to the counter electrode of each block divided into m, and the (m + 1) th counter electrode Assuming that a touch panel scanning voltage synchronized with a touch panel scanning voltage supplied to the counter electrode of each of the blocks divided into m is supplied to the electrodes, currents flowing through the plurality of detection electrodes Based on this, it is determined whether it is noise or water droplets.

It is a disassembled perspective view which shows schematic structure of the in-cell type liquid crystal display device which incorporated the touch panel in the inside of a liquid crystal display panel. It is a figure explaining the counter electrode and detection electrode in the liquid crystal display device shown in FIG. It is a schematic sectional drawing which expands and shows a part of cross section of the display part of the liquid crystal display device shown in FIG. 1 is a block diagram showing an overall schematic configuration of a touch panel in an in-cell type liquid crystal display device as a premise of the present invention. It is a figure for demonstrating the detection principle of a touch panel in the in-cell type liquid crystal display device used as the premise of this invention. FIG. 6 is a timing diagram of touch detection operation of a touch panel in an in-cell type liquid crystal display device as a premise of the present invention. FIG. 5 is a circuit diagram showing a more specific circuit configuration of the detection circuit shown in FIG. 4. 8 is a timing chart for explaining the operation of the circuit shown in FIG. 7. FIG. 5 is a diagram for explaining timings when a touch panel is detected and pixels are written in an in-cell type liquid crystal display device. FIG. 3 is a timing chart of driving a liquid crystal display panel and driving a sensor electrode in an in-cell type liquid crystal display device as a premise of the present invention. FIG. 5 is a diagram showing specifications of a register 1051 and a register 1052 shown in FIG. It is a figure which shows the touch-panel scanning timing of the in-cell type liquid crystal display device used as the premise of this invention. It is a figure which shows the touch-panel scanning timing of the modification of the in-cell type liquid crystal display device used as the premise of this invention. FIG. 3 is a diagram for explaining a noise detection method for a touch panel in the in-cell type liquid crystal display device according to the first embodiment. It is a graph which shows RAW data when there is no noise detected with a detection electrode by the noise detection method of the touch panel of Example 1. 6 is a graph showing noise RAW data detected by the detection electrode of the touch panel according to the first embodiment when the noise frequency is other than an integral multiple of the horizontal scanning frequency (external noise frequency ≠ an integral multiple of the horizontal scanning frequency). is there. RAW data in the case where the noise frequency detected by the detection electrode of the touch panel according to the first embodiment is a noise that is substantially equal to an integer multiple of the horizontal scanning frequency (external noise frequency ≈ integer multiple of the horizontal scanning frequency). It is a graph to show. 5 is a graph showing RAW data of detection electrodes in which noise is detected and data after passing through an averaging filter in the touch panel of Example 1. 6 is a flowchart illustrating a touch position detection process of the in-cell type liquid crystal display device according to the first embodiment. It is a figure for demonstrating the imaginary touch "ghost" produced in the position different from a touch position in a touch panel. It is a figure which shows the touch reaction by a water droplet. It is a figure which shows the touch reaction by external noise. It is the figure which showed RAW data distribution by an aerial electrode. It is a figure which shows the raw data change of the aerial electrode at the time of external noise generation | occurrence | production. It is a figure which shows the RAW data change of the aerial electrode at the time of water droplet adhesion. 12 is a flowchart of a touch position detection process of the display device according to the second embodiment. It is a figure for demonstrating the averaging process when only a water droplet adheres to a panel. It is a figure for demonstrating the averaging process when only a water droplet adheres to a panel. It is a figure for demonstrating the averaging process when only a water droplet adheres to a panel. It is a figure for demonstrating the averaging process when a water droplet adheres to a panel and a finger is touched. It is a figure for demonstrating the averaging process when a water droplet adheres to a panel and a finger is touched. It is a figure for demonstrating the averaging process when a water droplet adheres to a panel and a finger is touched.

Hereinafter, examples will be described with reference to the drawings. It should be noted that the disclosure is merely an example, and those skilled in the art can easily conceive of appropriate modifications while maintaining the gist of the invention are naturally included in the scope of the present invention. In addition, the drawings may be schematically represented with respect to the width, thickness, shape, and the like of each part in comparison with actual aspects for the sake of clarity of explanation, but are merely examples, and the interpretation of the present invention is not limited. It is not limited. In addition, in the present specification and each drawing, elements similar to those described above with reference to the previous drawings are denoted by the same reference numerals, and detailed description may be omitted as appropriate.
First, an in-cell liquid crystal display device will be described with reference to FIGS.
FIG. 1 is an exploded perspective view showing a schematic configuration of an in-cell type liquid crystal display device in which a touch panel is built in the liquid crystal display panel.
In FIG. 1, reference numeral 2 is a first substrate (hereinafter referred to as a TFT substrate), reference numeral 3 is a second substrate (hereinafter referred to as a CF substrate), reference numeral 21 is a counter electrode (also referred to as a common electrode), and reference numeral 5 is a liquid crystal driver. IC, reference numeral MFPC is a main flexible wiring board, reference numeral 40 is a front window, and reference numeral 53 is a connecting flexible wiring board.
In the liquid crystal display device shown in FIG. 1, the back side transparent conductive film (CD) on the CF substrate 3 is divided into strip-shaped patterns to form the detection electrodes 31 of the touch panel, which are opposed to each other formed inside the TFT substrate 2. The electrode 21 is divided into strip-shaped patterns, that is, divided into a plurality of blocks, which are also used as scanning electrodes for the touch panel, thereby reducing the number of touch panel substrates used in ordinary touch panels. In the liquid crystal display device shown in FIG. 1, a circuit for driving the touch panel is provided inside the liquid crystal driver IC (5).

Next, the counter electrode 21 and the detection electrode 31 of the liquid crystal display device shown in FIG. 1 will be described with reference to FIG.
As described above, the counter electrode 21 is provided on the TFT substrate 2, but a plurality of (for example, about 32) counter electrodes 21 are commonly connected at both ends and are connected to the counter electrode signal line 22. .
In the liquid crystal display device shown in FIG. 2, the strip-shaped counter electrode 21 also serves as a scanning electrode (Tx), and the detection electrode 31 constitutes a detection electrode (Rx).
Therefore, the counter electrode signal includes a counter voltage used for image display and a touch panel scanning voltage used for detecting the touch position. When the touch panel scanning voltage is applied to the counter electrode 21, a detection signal is generated in the detection electrode 31 that is arranged with a certain distance from the counter electrode 21 and constitutes a capacitor. This detection signal is taken out through the detection electrode terminal 36.
Note that dummy electrodes 33 are formed on both sides of the detection electrode 31. The detection electrode 31 extends toward the dummy electrode 33 at one end portion to form a T-shaped detection electrode terminal 36. In addition to the counter electrode signal line 22, various wirings and terminals such as the drive circuit input terminal 25 are formed on the TFT substrate 2.

FIG. 3 shows a schematic cross-sectional view in which a part of the cross section of the display portion in the liquid crystal display device shown in FIG. 1 is enlarged.
As shown in FIG. 3, the TFT substrate 2 is provided with a pixel portion 200, and the counter electrode 21 is used for image display as a part of the pixel. A liquid crystal composition 4 is sandwiched between the TFT substrate 2 and the CF substrate 3. The detection electrode 31 provided on the CF substrate 3 and the counter electrode 21 provided on the TFT substrate 2 form a capacitance, and when a drive signal is applied to the counter electrode 21, the voltage of the detection electrode 31 changes.
At this time, as shown in FIG. 3, when a conductor such as a finger 502 approaches or contacts through the front window 40, the capacitance changes and the voltage generated at the detection electrode 31 is compared with the case where there is no proximity / contact. Change.
Thus, by detecting a change in capacitance generated between the counter electrode 21 and the detection electrode 31 formed on the liquid crystal display panel, the liquid crystal display panel can be provided with a touch panel function.

FIG. 4 is a block diagram showing an overall schematic configuration of the touch panel in the in-cell type liquid crystal display device as a premise of the present invention.
In FIG. 4, reference numeral 101 is an LCD driver, reference numeral 102 is a sequencer, reference numeral 103 is a touch panel scanning voltage generation circuit, reference numeral 104 is a delay circuit, reference numeral 106 is a decoder circuit, reference numeral 107 is a touch panel, reference numeral 108 is a detection circuit, reference numeral 1051, Reference numeral 1052 denotes a register.
The touch panel 107 is formed with electrode patterns (scanning electrodes (Tx1 to Tx5) and detection electrodes (Rx1 to Rx5)) that are sensor terminals for detecting a user's touch.
Since the in-cell type liquid crystal display device which is the premise of the present invention has a touch panel function built in the liquid crystal display panel, the strip-shaped counter electrode 21 shown in FIG. 2 also serves as the scanning electrode (Tx), and the detection electrode 31 constitutes a detection electrode (Rx).
The LCD driver 101 sends synchronization signals (vertical synchronization signal (Vsync) and horizontal synchronization signal (Hsync)) for displaying an image on the liquid crystal display panel to the sequencer 102.
The sequencer 102 controls the touch detection operation timing by controlling the touch panel scanning voltage generation circuit 103, the delay circuit 104, the decoder circuit 106, and the detection circuit 108.
The touch panel scanning voltage generation circuit 103 generates and outputs a touch panel scanning voltage (Vstc) for driving the scanning electrodes (Tx1 to Tx5).

The delay circuit 104 delays the touch panel scanning voltage (Vstc) input from the touch panel scanning voltage generation circuit 103 by a delay amount instructed by the sequencer 102. The sequencer 102 determines the delay amount based on the parameters stored in the registers (1051, 1052).
The register 1051 is a register that stores a unit delay time, and the register 1052 is a register that stores a maximum delay time. The unit delay time stored in the register 1051 is a unit time for delaying the touch panel scanning voltage (Vstc), and is a parameter for determining the driving cycle of the touch panel scanning voltage (Vstc).
The maximum delay time stored in the register 1052 is the maximum time for delaying the touch panel scanning voltage (Vstc), and is a parameter that defines an allowable range for changing the timing of the touch panel scanning voltage (Vstc).
The decoder circuit 106 is an analog switch (demultiplexer) that outputs a touch panel scanning voltage (Vstc) to one of the scanning electrodes (Tx1 to Tx5) based on a selection signal input from the sequencer 102.
The detection circuit 108 includes an inter-electrode capacitance (mutually) at the intersection of one scan electrode to which the touch panel scan voltage (Vstc) is supplied and each detection electrode (Rx1 to Rx5) among the scan electrodes (Tx1 to Tx5). Capacity).

FIG. 5 is a diagram for explaining the detection principle of the touch panel in the in-cell type liquid crystal display device as a premise of the present invention.
FIG. 6 is a timing chart of the touch detection operation in the in-cell type liquid crystal display device which is a premise of the present invention.
The sequencer 102 controls the touch panel scanning voltage generation circuit 103 and the like, and sequentially supplies the touch panel scanning voltage (Vstc) to the scanning electrodes (Tx1 to Tx5) while synchronizing with the vertical synchronization signal (Vsync) and the horizontal synchronization signal (Hsync). To do. Here, as shown in FIGS. 5 and 6, the touch panel scanning voltage (Vstc) is supplied to each scanning electrode a plurality of times (eight times in FIG. 6). In addition, the code | symbol C of FIG. 5 is a cross capacitance of a scanning electrode (Tx1) and a detection electrode (Rx4).
As shown in FIG. 6, the detection circuit 108 integrates the currents flowing through the detection electrodes (Rx1 to Rx5) (integration in the negative direction in FIG. 6), and records the reached voltage values (ΔVa, ΔVb). To do.
When the finger (conductor) is touching the vicinity of the intersection of the scanning electrode (Tx) and the detection electrode (Rx), a current flows to the finger, so that the voltage value of the integration result changes.
For example, in FIG. 6, since there is no finger near the intersection of the scanning electrode (Tx1) and the detection electrode (RxN) (the state without touch shown by NA in FIG. 6), the voltage obtained by integrating the current flowing through the detection electrode is It becomes a non-touch level (LA).
On the other hand, since the finger exists near the intersection of the scanning electrode (Tx2) and the detection electrode (RxN) (the state with touch shown by NB in FIG. 6), a current also flows to the finger, The voltage obtained by integrating the flowing current is a voltage having a higher potential than the non-touch level (LA). The touch position can be detected from this change amount (touch signal).

FIG. 7 is a circuit diagram showing a more specific circuit configuration of the detection circuit 108 shown in FIG.
FIG. 8 is a timing chart for explaining the operation of the circuit shown in FIG.
In FIG. 7, reference numeral 10 denotes an integration circuit, reference numeral 11 denotes a sample and hold circuit, reference numeral 12 denotes a 10-bit AD converter, and reference numeral 13 denotes a memory (hereinafter referred to as RAW data) output from the AD converter 12. RAM).
Hereinafter, the operation of the circuit shown in FIG. 7 will be described with reference to FIG. In FIG. 8, Hsync is a horizontal synchronization signal.
(1) Before detecting (integrating) the current flowing through each of the detection electrodes (Rx1 to Rxn), the switch (S1) is turned on to reset the integration circuit 10, and the switch (S3) is turned on to (Rx1 to Rxn) are reset (period A1 in FIG. 8).
When the reference voltage (VREF) is 4V (VREF = 4V), the output of the integrating circuit 10 is precharged to 4V, and each of the detection electrodes (Rx1 to Rxn) is precharged to 4V.
(2) Next, after turning off the switch (S1) and the switch (S3), the touch panel scanning voltage (Vstc) is output from one of the scanning electrodes (Tx1 to Txm), and the switch is synchronized with this. Integration is performed with (S2) ON (period B1 in FIG. 8).
As a result, a current flows through a path of one of the scan electrodes (Tx1 to Txm) ⇒crossing capacitance (Cxy) ⇒integration capacitance (CINT), and the output voltage (VINT) of the integration circuit 10 decreases.
Where VINT = VREF−Vstc * (Cxy / CINT)

(3) After integration in the integration circuit 10, the switch (S2) is turned off and the switch (S3) is turned on to precharge the detection electrodes (Rx1 to Rxn) to 4 V (period A2 in FIG. 8).
(4) The integration operation in the integration circuit 10 of (2) is repeated, and the voltage is accumulated (period B2,... In FIG. 8).
(5) After the integration in the integration circuit 10 is completed (after the period Bn in FIG. 8), the switch (S4) is turned on, and the sample and hold circuit 11 samples and holds (period C in FIG. 8). (S6) is sequentially turned ON, AD conversion is performed by the AD converter 12, and RAW data for the scanning electrodes of the respective detection electrodes (Rx1 to Rxn) is stored in the memory (RAM) 13.
When the AD converter 12 is a 10-bit AD converter, the RAW data is in the range of 0 (integral 0 V) to 1023 (integral 4 V). 0 is the least significant data and 1023 is the most significant data.
(6) Since the cross capacitance (Cxy) is at untouched> touch, as shown in delta Va, delta Vb in FIG. 6, drop difference occurs in the integrated output voltage of the integration circuit 10 (VINT), A threshold value is provided here to detect touch.
In general, the AD converter 12, if the AD converter 10bit, the voltage of the delta Va shown in FIG. 6, the digital data after the AD conversion becomes 250 to 350 in decimal. These 250 to 350 are operating points in normal detection processing.

FIG. 9 is a diagram for explaining the timing when the touch panel is detected and when the pixel is written in the in-cell type liquid crystal display device. In FIG. 9, T3 is a blanking period, Vsync is a vertical synchronization signal, and Hsync is a horizontal synchronization signal.
9A shows the pixel writing timing from the first display line to the 1280 display line in the pixel writing period (T4) of one frame, and FIG. 9B shows the opposite of each block divided into 20 blocks. The touch panel detection timing in an electrode is shown.
As shown in FIG. 9, the counter electrode of an arbitrary display line functions as a scan electrode (Tx), and the scan operation (VCOM scan) at the time of touch panel detection is different from the gate scan (LCD Gate scan) for pixel writing. Do it in place.
As described with reference to FIG. 9, the gate scan and the touch panel scan are performed on different display lines. However, there is a parasitic capacitance between the video line and the counter electrode 21 and between the scan line and the counter electrode 21. Therefore, the detection sensitivity at the time of touch panel detection is reduced due to the fluctuation of the video voltage (VDL) on the video line or the noise generated at the rise or fall of the scanning voltage (VGL).
Therefore, in the in-cell type liquid crystal display device which is a premise of the present invention, the touch position detection operation is performed during a period when there is no fluctuation of the voltage (VDL) on the video line, or when the scanning voltage (VGL) rises or falls. Executed.

FIG. 10 is a timing diagram for driving a liquid crystal display panel and driving a sensor electrode in an in-cell type liquid crystal display device as a premise of the present invention.
In FIG. 10, VGL is a scanning voltage on the scanning line, VDL is a video voltage on the video line, Vcom is a counter voltage (also referred to as a common voltage) supplied to the counter electrode 21, Vstc is a touch panel scanning voltage, and 1H is one horizontal scanning period. , Txs is a touch panel scanning start waiting period.
Since the in-cell type liquid crystal display device which is the premise of the present invention employs dot inversion as an alternating drive method, the counter voltage is a voltage of Vcom having a constant potential.
In the in-cell type liquid crystal display device incorporating a touch panel function in the liquid crystal display panel, the strip-like counter electrode 21 shown in FIG. 2 is also operated as a scanning electrode (Tx) for touch detection. (A in FIG. 10) and the touch position detection operation (B in FIG. 10) need to be completely time-divisionally controlled synchronously.
As described above, in the in-cell type liquid crystal display device which is a premise of the present invention, the touch position detection operation is performed by the fluctuation of the video voltage (VDL) on the video line or the rise or fall of the scanning voltage (VGL). It is executed during the period when there is no (TA period in FIG. 10 or TB period).

FIG. 11 is a diagram showing specifications of the register 1051 and the register 1052 shown in FIG.
The register name “T PC _TXDLY” shown in FIG. 11 is the register 1051 shown in FIG. 4, the parameter is “unit delay time (t_txdly)”, and the unit delay time is 0 to 0.286 us. It is set up to 18.00us.
Further, the register of “T PC _TXMAXD” shown in FIG. 11 is the register 1052 shown in FIG. 4, the parameter is “maximum delay time (t_txmaxd)”, and the maximum delay time is 0-18. It is set up to 00us. However, the condition t_txdly <t_txmaxd needs to be satisfied.
FIG. 12 is a diagram showing the touch panel scanning timing of the in-cell type liquid crystal display device which is a premise of the present invention. In FIG. 12, 1H is one horizontal scanning period, and TxH is a touch panel scanning period.
In the in-cell type liquid crystal display device as a premise of the present invention, when the touch panel scanning voltage (Vstc) is supplied to the same scanning electrode (Tx) a plurality of times (for example, 32 times) over a plurality of horizontal scanning periods. The timing for supplying the touch panel scanning voltage (Vstc) to the scanning electrode (Tx) is delayed by the unit delay time stored in the register 1051 every horizontal scanning period. However, the maximum delay time stored in the register 1052 is not exceeded.

In the in-cell type liquid crystal display device which is the premise of the present invention, as shown in FIG. 12, in the first horizontal scanning period, the timing for supplying the touch panel scanning voltage (Vstc) to the scanning electrode (Tx) is the horizontal synchronization signal. Although it is a time after a predetermined waiting time (t_txwait) has elapsed from the rising time of (Hsync), the timing of supplying the touch panel scanning voltage (Vstc) to the scanning electrode (Tx) in the second horizontal scanning period is horizontal synchronization. It becomes a time point (t_txwait + t_txdly) after a period obtained by adding a unit delay time (t_txdly) to a predetermined waiting time (t_txwait) from the rising time of the signal (Hsync), and in the n (0 ≦ n ≦ 31) th horizontal scanning period, The timing for supplying the touch panel scanning voltage (Vstc) to the scanning electrode (Tx) is from the rising edge of the horizontal synchronization signal (Hsync). A a constant latency (t_txwait) n × unit delay time (n × t_txdly) time after period of time obtained by adding the (t_txwait + n × t_txdly).
As described above, in the in-cell type liquid crystal display device which is the premise of the present invention, the touch panel scanning voltage (Vstc) is applied to the same scanning electrode (Tx) a plurality of times (for example, 32 times) over a plurality of horizontal scanning periods. When supplying, the timing of supplying the touch panel scanning voltage (Vstc) to the scanning electrode (Tx) in the n (0 ≦ n ≦ 31) horizontal scanning period is (t_txwait + de
ley; deley = n × t_txdly). When (n × t_txdly) becomes equal to or longer than the maximum delay time (t_txmaxd) (n × t_txdly ≧ t_txmaxd), (deley = deley−n × t_txdly) is set.

Hereinafter, setting examples of the register (TPC_TXDLY) 1051 and the register (TPC_TXMAXD) 1052 of the in-cell type liquid crystal display device which is a premise of the present invention will be described.
Touch panel scanning period (TxH)> 1 horizontal scanning period (1H) [Example 1]
Register (TPC_TXDLY) = 1, Register (TPC_TXMAXD) = 5
Delay number = 0, 1, 2, 3, 4, 0, 1, ...
[Example 2]
Register (TPC_TXDLY) = 2, Register (TPC_TXMAXD) = 5
Delay number = 0, 2, 4, 1, 3, 0, 2, ...
When touch panel scanning period (TxH) <1 horizontal scanning period (1H) [Example 3]
Register (TPC_TXDLY) = 9, Register (TPC_TXMAXD) = 10
Delay number = 0, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0, 9, ...

11 and 12, the timing for supplying the touch panel scanning voltage (Vstc) to the scanning electrode (Tx) for each horizontal scanning period is within a range not exceeding the maximum delay time stored in the register 1052. Although the unit delay time stored in the register 1051 is delayed, the present invention is not limited to this, and the following method may be adopted.
Hereinafter, modifications of the in-cell type liquid crystal display device which is a premise of the present invention will be described. FIG. 13 is a diagram showing touch panel scanning timing of a modified example of the in-cell type liquid crystal display device as a premise of the present invention.
In the modification of the in-cell type liquid crystal display device which is a premise of the present invention, 16 registers TXDLY1 [3: 0] to TXDLY16 [3: 0] are used in addition to the registers 1051 and 1052 shown in FIG. It is done.
When k is an integer from 1 to 16 (1 ≦ k ≦ 16) and n is an integer greater than or equal to 0 (0 ≦ n), TXDLYk [3: 0] performs touch panel scanning every (k + 16n) horizontal scanning period. A time width for delaying the timing of supplying the voltage (Vstc) to the scan electrode (Tx) is set. That is, TXDLYk [3: 0] is from the time after the rising edge of the horizontal synchronization signal (Hsync) to the timing after the predetermined waiting time (t_txwait) has elapsed until the timing of supplying the touch panel scanning voltage (Vstc) to the scanning electrode (Tx). The number of unit delay times (t_txdly) is set.
As a result, as shown in FIG. 13, the delay time from when the horizontal synchronization signal (Hsync) rises to when the touch panel scanning voltage (Vstc) is supplied to the scanning electrode (Tx) after a predetermined waiting time (t_txwait) has elapsed. The width can be set randomly.
TXDLY1 = 0, TXDLY2 = 0, TXDLY3 = 0, TXDLY4 = 1, TXDLY5 = 0, TXDLY6 = 15, TXDLY7 = 0, TXDLY1 [3: 0] to TXDLY16 [3: 0] Touch panel scan when TXDLY8 = 7, TXDLY9 = 0, TXDLY10 = 2, TXDLY11 = 0, TXDLY12 = 8, TXDLY13 = 0, TXDLY14 = 4, TXDLY15 = 0, TXDLY16 = 12, and the time width is 0 Table 1 shows the increase / decrease number (Δ) of the unit delay time (t_txdly) with respect to the period (TxH) and the value of the touch panel scanning period (TxH).

In a normal touch panel, the frequency of driving the electrodes (scanning electrodes, detection electrodes) of the touch panel is adjusted in order to reduce the influence of the noise source of the terminal on which the touch panel is mounted on the touch detection.
On the other hand, in an in-cell type liquid crystal display device with a built-in touch panel function in the liquid crystal display panel, the liquid crystal display panel is driven by referring to the synchronization signal of the liquid crystal display panel in order to avoid the influence of noise generated from the liquid crystal display panel. The touch panel is scanned using no timing. For this reason, the drive frequency of the touch panel depends on the drive frequency of the liquid crystal display panel, and there is a problem that it cannot be freely adjusted.
In the above-described in-cell type liquid crystal display device which is the premise of the present invention and the modification of the in-cell type liquid crystal display device which is the premise of the present invention, the drive frequency of the touch panel can be freely adjusted. It is possible to reduce the influence of the noise source of the terminal equipped with the touch detection.
However, if the noise frequency is almost equal to an integer multiple of the horizontal scanning frequency (external noise frequency ≈ integer multiple of the horizontal scanning frequency), external noise will be input, causing the integration circuit in the detection circuit to misintegrate, There was a problem of generating "ghost".
For example, as shown in FIG. 20, when a low-cost charger is connected to a portable terminal equipped with a touch panel, the touch position (A in FIG. 20) differs from noise generated from the charger, so-called AC charger noise. An imaginary touch “ghost” (FIG. 20B) is induced at the position. Note that AC charger noise is common-mode noise, so that problems such as false detection do not occur in a non-touch state even during charging.

The in-cell type liquid crystal display device according to the present embodiment is characterized in that the above-described imaginary touch “ghost” is identified, and the influence of the imaginary touch “ghost” in touch detection is reduced. Note that the configuration of the in-cell display device of this embodiment is basically the same as that of FIGS. 1 to 4 and 7 except for the portion corresponding to FIG.
FIG. 14 is a diagram for explaining a noise detection method for a touch panel in the in-cell type liquid crystal display device according to the first embodiment. FIG. 15 is a graph showing RAW data when there is no noise detected by the detection electrode by the noise detection method of the touch panel of the first embodiment. FIG. 16 is a graph showing RAW data of noise that is detected by the detection electrodes by the touch panel noise detection method of the first embodiment and whose noise frequency is not an integral multiple of the horizontal scanning frequency. FIG. 17 is a graph showing RAW data in the case where the noise frequency detected by the detection electrode by the touch panel noise detection method of Example 1 is substantially equal to an integral multiple of the horizontal scanning frequency.
In the touch panel of this embodiment, it is assumed that an imaginary counter electrode (Txv) exists as shown in FIG. 14A with respect to the scanning electrodes (Tx0 to Tx7) of the actual touch panel, and B in FIG. As shown in FIG. 4, the touch panel scanning voltage synchronized with the touch panel scanning voltage (Vstc) supplied to the actual scanning electrodes (Tx0 to Tx7) of the touch panel is supplied to the imaginary counter electrode (Txv). Assuming that, noise is detected based on currents flowing through the plurality of detection electrodes (Rx1 to Rx6).
Here, the touch panel scanning voltage (Vstc) for the imaginary counter electrode (Txv) is output from the touch panel scanning voltage generation circuit 103 shown in FIG.
In synchronization with the imaginary touch panel scanning voltage (Vstc) for the imaginary counter electrode (Txv), the integration circuit 10 is operated to detect noise.
As shown in FIG. 15, when there is no noise, there is no inflow of charge into the integrating circuit 10, so the output voltage (VINT) of the integrating circuit 10 maintains the reference voltage (VREF) of 4V. Therefore, the value of the RAW data after AD conversion of the output voltage (VINT) of the integration circuit 10 by the AD converter 12 is 1023 in decimal notation, and as shown in FIG. It becomes a point. Also, C in FIG. 15 is a noise determination threshold (Th) line, and the decimal value of the RAW data after AD conversion of the output voltage (VINT) of the integration circuit 10 by the AD converter 12 is the noise determination threshold. When it is smaller than the threshold (Th) line, it is determined as noise. In FIG. 15, FIG. 16, FIG. 17, FIG. 18, FIG. 24 and FIG. 25, the number given to one memory on the horizontal axis is the number of times the sample and hold circuit 11 has sampled and held.

As shown in FIG. 16, when the noise frequency is other than an integral multiple of the horizontal scanning frequency (external noise frequency ≠ integer multiple of the horizontal scanning frequency), there is an inflow of charge into the integrating circuit 10, but the integrating circuit 10 As a result, the output voltage (VINT) of the integration circuit 10 is maintained around 4 V of the reference voltage (VREF). Therefore, as shown in FIG. 16B, the value of the RAW data after AD conversion of the output voltage (VINT) of the integration circuit 10 by the AD converter 12 maintains a value near 1023 in decimal.
As shown in FIG. 17, when the noise frequency is approximately equal to an integer multiple of the horizontal scanning frequency (external noise frequency≈an integer multiple of the horizontal scanning frequency), the charge inflow direction to the integrating circuit 10 is periodically The output voltage (VINT) of the integrating circuit 10 changes greatly. Therefore, as shown in C of FIG. 17, the RAW data value after AD conversion of the output voltage (VINT) of the integration circuit 10 by the AD converter 12 changes greatly.
The decimal value of the RAW data after AD conversion of the output voltage (VINT) of the integrating circuit 10 by the AD converter 12 is shown in C of FIG. If it falls below the threshold (Th) line for noise judgment shown, it is judged as noise.

As shown in FIG. 17, when noise is determined, an imaginary touch “ghost” is then identified.
The identification of this fictitious touch “ghost” uses the fact that the operating point of the RAW data is different. That is, the operating point of the RAW data is extracted by passing the RAW data through the averaging filter.
FIG. 18 is a graph showing the RAW data of the detection electrode in which noise is detected and the RAW data after passing through the averaging filter in the touch panel of Example 1.
In this embodiment, AC charger noise is assumed, and the fictitious touch “ghost” due to this AC charger noise is generated on the same detection electrode. Therefore, in FIG. 18, noise is applied to the Rx6 detection electrode shown in FIG. The graph when is detected is illustrated.
In FIG. 18, Tx0_Rx6 indicates RAW data obtained from the detection electrode of Rx6 when the touch panel scanning voltage (Vstc) is applied to the scanning electrode of Tx0.
Similarly, Tx1_Rx6 represents the RAW data obtained from the detection electrode of Rx6 when the touch panel scanning voltage (Vstc) is applied to the scanning electrode of Tx1, and Tx2_Rx6 represents the touch panel scanning voltage (Vst) of the scanning electrode of Tx2.
When c) is applied, RAW data obtained from the detection electrode of Rx6, Tx3_Rx6 is RAW data obtained from the detection electrode of Rx6 when a touch panel scanning voltage (Vstc) is applied to the scan electrode of Tx3, and Tx4_Rx6 is , RAW data obtained from the detection electrode Rx6 when the touch panel scanning voltage (Vstc) is applied to the scanning electrode Tx4, and Tx5_Rx6 is the detection of Rx6 when the touch panel scanning voltage (Vstc) is applied to the scanning electrode Tx5. RAW data obtained from the electrodes, Tx6_Rx6 represents the RAW data obtained from the detection electrodes of Rx6 when a touch panel scanning voltage (Vstc) is applied to the scanning electrodes of Tx6, Tx7_Rx6 represents the touch panel scanning voltage ( Rx6 detection when Vstc) is applied It shows RAW data obtained from the pole.
FIG. 18B shows the RAW data after the RAW data shown in the graph of FIG. 18A is passed through the averaging filter.
As shown in FIG. 18B, when noise is detected, an electrode having the maximum operating point (scanning electrode intersecting with the detection electrode of Rx6) in the RAW data is determined as an actual touch electrode. Then, the electrode portions whose operating points are below the ghost determination threshold (Th1) line are determined to be ghosts. In FIG. 18B, A is an actual touch electrode (Tx4_Rx6), B is an electrode adjacent to the touch electrode (Tx5_Rx6), and C is an electrode for generating an aerial touch “ghost”.

FIG. 19 is a flowchart illustrating the touch position detection process of the liquid crystal display device according to the first embodiment.
When the touch position detection process is executed, the integration circuit 10 is operated in synchronization with the imaginary touch panel scanning voltage (Vstc) for the imaginary counter electrode (Txv) to determine whether there is noise (step) S110).
If it is determined in step S110 that there is no noise, normal touch position detection processing is executed (step S111), and the coordinates of the touch position are reported (step S112).
If it is determined in step S110 that there is noise, exception processing (averaging filter processing) is executed (step S113), and it is determined whether or not the fictitious touch “ghost” can be identified (step S114).
If the fictitious touch “ghost” can be identified in step S114, the touch position detection process is executed with reference to the information of the fictitious touch “ghost”, and the coordinates of the touch position are reported (step S115).
If the fictitious touch “ghost” cannot be identified in step S115, the touch position detection process is not executed and the coordinates of the touch position are not reported (step S116).
A program corresponding to the flowchart of FIG. 19 is stored in a storage device such as a flash memory in the detection circuit 108, and is executed by a central processing unit (CPU) in the detection circuit 108 with reference to the RAW data in the memory 13. The

The above-described first embodiment is summarized as follows.
(1) The liquid crystal display device includes a first substrate (2), a second substrate (3), and a liquid crystal (4) sandwiched between the first substrate (2) and the second substrate (3). A plurality of pixels (200) arranged in a matrix.
The second substrate (3) has a plurality of detection electrodes (Rx) of the touch panel.
Each pixel (200) has a pixel electrode and a counter electrode (21).
When m is an integer of 2 or more (m ≧ 2), the counter electrode (21) is divided into m blocks.
The counter electrode (21) of each block divided into m is provided in common for each pixel of a plurality of continuous display lines.
The counter electrode (21) of each block divided into m is also used as the scanning electrode (Tx) of the touch panel.
A driving circuit (5) for supplying a counter voltage and a touch panel scanning voltage (Vstc) to the counter electrode (21, Tx) of each block divided into m pieces, and a current flowing through the plurality of detection electrodes (Rx) And a detection circuit (108) for detecting presence or absence of touch.
The drive circuit (5) sequentially supplies the touch panel scanning voltage (Vstc) to the counter electrode (21, Tx) of each block divided into m pieces.
When the touch panel scanning voltage (Vstc) is supplied to the counter electrode (21, Tx) of each block divided into (a), (a) the detection circuit (108) is supplied to the plurality of detection electrodes (Rx). The presence or absence of touch is detected based on the flowing current, and (b) the (m + 1) th counter electrode (Txv) exists for the counter electrode (21) of each block divided into m blocks. Assuming that the (m + 1) th counter electrode (Txv) is synchronized with the touch panel scanning voltage (Vstc) supplied to the counter electrode (21, Tx) of each block divided into m blocks. Assuming that the touch panel scanning voltage is supplied, noise is detected based on currents flowing through the plurality of detection electrodes (Rx).
(2) The detection circuit (108) includes a plurality of integration circuits (10) provided for each of the plurality of detection electrodes (Rx), and an AD converter that converts output voltages of the plurality of integration circuits (10) into digital data. 12).
Each integrating circuit (10) is supplied to the counter electrode (21, Tx) of each block divided into m when the touch panel scanning voltage (Vstc) is supplied and to the imaginary (m + 1) th counter electrode. When an imaginary touch panel scanning voltage (Vstc) is supplied, the current flowing through each detection electrode (Rx) is divided into m counter electrodes (21, Tx) and imaginary (m + 1). Integration is performed for each counter electrode (Txv).
(3) In the above (a), a plurality of digital data converted by the AD converter (10) has a value closer to the lowest data than the intermediate value between the lowest data and the highest data as a first operating point. The value of the digital data when the integrated value for each counter electrode (21, Tx) of each block divided into m pieces of the integrating circuit (10) of the digital signal is converted by the AD converter (10) is the first operating point. It is determined that there is a touch when the difference between the first operation point and the first data is greater than a predetermined threshold value 1 and no touch.
(4) In (b) above, the fictitious () of the plurality of integrating circuits (10) is set with the most significant data (A in FIG. 17) in the digital data converted by the AD converter (10) as the second operating point. The digital data value when the integral value of the (m + 1) th counter electrode (Txv) is converted by the AD converter (10) is a value between the second operating point and the least significant data, and When the difference from the second operating point is larger than a predetermined threshold value 2 (C (Th) in FIG. 17), it is determined as noise.
(5) The digital data converted by the AD converter (10) is 10-bit data. The first operating point has a value of 250 to 350 in decimal notation. The second operating point is a value close to 1023 in decimal.
(6) The detection circuit (108) is configured to identify an imaginary touch caused by the noise when the noise is detected in (c) (b).
In (c), the integration for each counter electrode (21, Tx) of each block divided into m blocks in the integration circuit (10) corresponding to the detection electrode (Rx) in which noise is detected in (b). The digital data when the value is converted by the AD converter (10) is passed through the averaging filter, and the data value among the data after passing through the averaging filter has the maximum value (A in FIG. 18). The object is determined as an actual touch electrode, and the data value is a value between the maximum value (A in FIG. 18) and the lowest data, and a difference between the maximum value (A in FIG. 18) is predetermined. An electrode larger than the threshold value 3 (Th1) is identified as an imaginary touch electrode.
(7) In the touch detection process, when no noise is detected in (b), the normal touch position detection process is executed.
In (b), when noise is detected, if an imaginary touch caused by the noise can be identified in (c), touch position detection processing is performed with reference to the imaginary touch identified in (c). Run.
In (b), when noise is detected, touch position detection processing is not executed when an imaginary touch caused by the noise cannot be identified in (c).

As described above, according to the present embodiment, the noise frequency is substantially equal to an integer multiple of the horizontal scanning frequency by adding only software without adding hardware means (external noise frequency ≈ integer of horizontal scanning frequency). X) It is possible to reduce the influence of the fictitious touch “ghost” caused by the input of external noise and the integration circuit in the detection circuit causing erroneous integration.
In this embodiment, the “touch panel drive frequency is freely adjusted” in the above-described in-cell liquid crystal display device which is the premise of the present invention and the in-cell liquid crystal display device which is the premise of the present invention. By combining with the “Yes” technology, the influence of noise can be reduced, but this embodiment can also be applied to a general in-cell type liquid crystal display device.

The touch reaction between water droplets and external noise will be described with reference to FIGS. FIG. 21 is a diagram showing a touch reaction due to water droplets. FIG. 22 is a diagram showing a touch reaction due to external noise. The grid represents the intersection of the scan electrode and the detection electrode. The numbers in the squares indicate the strength of the touch, and are shown as relative values to the reference value. A large positive number indicates a strong touch. If there is no touch of the finger 502 to the touch panel 107, noise, or water droplets, the value appears as close to zero. Three numbers in parentheses indicate the X coordinate, the Y coordinate, and the strength of the touch position. For example, in (607, 226, 47), “607” represents the X coordinate of the touch position, “226” represents the Y coordinate of the touch position, and “47” represents the strength of the touch.
As shown in FIG. 21, the numbers of the touch (actual touch) TT of the finger 502 on the touch panel 107 and the imaginary touch WT around the water droplet 201 attached to the touch panel 107 are large. The actual touch TT number is larger than the imaginary touch WT number. As shown in FIG. 22, the numbers of the touch (actual) TT of the finger 502 on the touch panel 107 and the imaginary touch WT of external noise are large. The actual touch TT number is larger than the imaginary touch WT number.
When water droplets adhere to the touch panel of the in-cell display device, when comparing temporary detection data, a tendency similar to that of external noise is shown as shown in FIGS. In the case of external noise, if the touch panel is not touched, the effect of noise does not occur. However, since a fictitious touch occurs even if the water droplet is not touched, a situation in which no touch report is reported also occurs. For this reason, it is necessary to determine external noise and water droplets from the detection data, and to separate the processing by each.
However, when the determination is made only with the detection data of the scanning electrode (ordinary electrode) of the touch panel, the detection data of the entire panel surface is accumulated to some extent and analyzed, which complicates the algorithm and places a heavy load on the processing. In addition, there is a problem that a delay occurs in the touch report.

In the second embodiment, the external noise detection using the imaginary counter electrode (aerial electrode) in the first embodiment is applied to separate the external noise from the water droplets. The principle of separating external noise and water droplets will be described with reference to FIGS. Note that the configuration of the in-cell display device of the present embodiment is basically the same as that of the first embodiment. FIG. 23 is a diagram showing the RAW data distribution by the aerial electrodes. FIG. 24 is a diagram showing a change in RAW data of the aerial electrode when external noise occurs. FIG. 25 is a diagram showing a change in RAW data of the aerial electrode when a water droplet is attached. The numbers in the cells are RAW data and are represented in the range of 0 to 1023. The larger the number, the stronger the touch. Three numbers in parentheses indicate the X coordinate, the Y coordinate, and the strength of the touch position. Note that the RAW data at the aerial electrode (Txv) is a number close to 1023 if there is no noise.
For external noise and water droplets, characteristic data (the value of detection data is small) is detected on the normal electrode (Tx). In addition, as shown in FIGS. 24 and 25, data changes occur in the aerial electrode (Txv) in the case of external noise, but when a water droplet adheres, the change in the aerial electrode (Txv) is not observed. I can't.
For these reasons, monitoring the values of the normal electrode (Tx) and the aerial electrode (Txv) makes it possible to easily separate external noise and water droplets, and solve the problem of touch reporting by separating the processing. Can do.

Next, a touch position detection processing flow according to the second embodiment will be described with reference to FIG. FIG. 26 is a flowchart of the touch position detection process of the display device according to the second embodiment. The program corresponding to the flowchart of FIG. 26 is stored in a storage device such as a flash memory in the detection circuit 108, and is executed by the central processing unit (CPU) in the detection circuit 108 with reference to the RAW data in the memory 13. The
In step S200, detection data is acquired. RAW data is stored in the memory 13. In step 201, normal electrode detection data is determined. Detection of detection data using normal electrodes is based on the current flowing through multiple detection electrodes when touch panel scanning voltage is supplied to the counter electrodes of each of the m divided blocks. Is detected. The normal electrode utilizes the fact that characteristic RAW data is generated when water droplets or external noise occurs. When water droplets or external noise occurs, detection data is small. That is, the presence / absence of detection data below the threshold for water / noise determination is confirmed on the normal electrode. If “detection data <water droplet / noise determination threshold”, noise determination of the aerial electrode is performed in step S210. In step S202, touch detection is performed. If “detection data> touch determination threshold”, it is determined that there is a touch, and touch coordinates are calculated in step S203. If “detection data <touch determination threshold”, it is determined that there is no touch, the touch coordinates are cleared, and the process proceeds to step S204. In step S204, the touch coordinates are notified to the host.
In step S210, the detection data of the fictitious electrode is determined whether or not there is noise. The determination of the detection data by the fictitious electrode is based on the assumption that the (m + 1) -th counter electrode exists for the counter electrode of each block divided into m, and the (m + 1) -th counter electrode On the other hand, assuming that a touch panel scanning voltage synchronized with the touch panel scanning voltage supplied to the counter electrode of each block divided into m is supplied, noise is generated based on the current flowing through the plurality of detection electrodes. And whether it is a water drop or not. As shown in FIGS. 24 and 25, in the aerial electrode, there is a difference in the change in the RAW data between the water droplet and the external noise. If it is determined that noise has occurred, noise processing is performed in step S220. Note that the determination of noise is as described in FIGS. 14 to 17 of the first embodiment. If it is determined that there is no noise, a water droplet process is performed in step S230.

  The noise processing in step S220 will be described with reference to FIG. The fact that the operating points of the actual touch and noise RAW data are different is used. First, in step S221, the touch determination threshold used in touch determination (step S202) is changed. This changed touch determination threshold is called a ghost determination threshold (Th1). In step S222, an arithmetic average value of several frames (for example, 20 frames) is calculated for the RAW data as shown in FIG. 18A (the operation point of the RAW data is extracted by the averaging filter). The RAW data is as shown in (b). When performing touch determination in the next step 202, a ghost determination threshold is used. In the RAW data, an electrode having the maximum value of the operating point (scanning electrode intersecting with the detection electrode of Rx6) is determined as an actual touch electrode, and an electrode portion whose operating point is lower than the ghost determination threshold is determined as a ghost. . If there are a plurality of electrode portions exceeding the ghost determination threshold and an actual touch electrode cannot be determined, it is determined that the ghost cannot be identified, and the touch report is not performed.

The water droplet process in step S230 will be described with reference to FIGS. FIG. 27, FIG. 28 and FIG. 29 are diagrams for explaining the averaging process when only water droplets adhere to the panel. 30, FIG. 31 and FIG. 32 are diagrams for explaining the averaging process when a water droplet adheres to the panel and a finger is touched. The RAW data of the location where the water droplet is attached utilizes the fact that the center of the water droplet is small and the vicinity is large (imaginary touch). First, in step S231, the touch determination threshold value used in touch determination (step S202) is changed (the threshold value is increased). This changed touch determination threshold is referred to as a water drop determination threshold.
The touch intersection peripheral data averaging in step S232 when only water droplets adhere to the panel as shown in FIG. 27 will be described. As shown in FIG. 28, there are points (intersections where there is a touch reaction, local maximum values) T1 and T2 in the vicinity of the water droplets. The raw data at the intersection T1 is 488, and the raw data at the intersection T2 is 560. As shown in FIG. 29, the arithmetic average of the RAW data (303, 338, 324, 398, 488, 370, 413, 382, 416) of the intersection T1 and the surrounding area AR1 is about 381, and the intersection T1 The RAW data 488 becomes smaller. Similarly, the arithmetic average of the RAW data 300, 347, 404, 553, 560, 314, 363, 376, 310) of the intersection T2 and the surrounding area AR2 is about 392, which is based on the RAW data 560 of the intersection T2. Becomes smaller. Since the RAW data is small around the intersection where the touch reaction occurs, the RAW data becomes small when the peripheral data is averaged. When performing touch determination in the next step 202, a water droplet determination threshold is used. As a result of the touch determination, the touch reaction at the intersections T1 and T2 is canceled (not touched (NT)).
The touch intersection peripheral data averaging in step S232 when a water droplet adheres to a panel as shown in FIG. 30 and a finger is touched will be described. As shown in FIG. 31, there are points where the RAW data is large (intersection where there is a touch reaction, maximum value) T3 and T4 around the finger touch and the water drop. The raw data at the intersection T3 is 1009, and the raw data at the intersection T4 is 528. As shown in FIG. 32, the arithmetic average of the RAW data (529, 781, 468, 626, 1009, 683, 358, 630, 440) of the intersection T3 and the surrounding area AR3 is about 614, and the intersection T3 The RAW data 1009 becomes smaller. Similarly, the arithmetic average of the RAW data (281, 324, 308, 262, 528, 295, 346, 283, 357) of the intersection T4 and the surrounding area AR4 is about 332, and the RAW data 528 of the intersection T4. Smaller than. Since the RAW data is small around the intersection where the touch reaction occurs, the RAW data becomes small when the peripheral data is averaged. When performing touch determination in the next step 202, a water droplet determination threshold is used. As a result of the touch determination, the touch reaction at the intersection T4 is canceled (not touched (NT)), and only the intersection T3 is touched (TT).

The above-described second embodiment is summarized as follows.
(1) The display device includes a first substrate (2) having a pixel electrode and a counter electrode (21), a second substrate (3) having a plurality of touch panel detection electrodes (31, Rx), and a first substrate. A liquid crystal (4) sandwiched between (2) and the second substrate (3), and a drive circuit (5) for supplying a counter voltage and a touch panel scanning voltage (Vstc) to the counter electrode (21). And a detection circuit (108) for detecting presence / absence of touch based on currents flowing through the plurality of detection electrodes (Rx).
When m is an integer of 2 or more (m ≧ 2), the counter electrode (21) is divided into m blocks.
The counter electrode (21) of each block divided into m is provided in common for each pixel (200) of a plurality of continuous display lines.
The counter electrode (21) of each block divided into m also serves as the scanning electrode (Tx) of the touch panel.
The drive circuit (5) sequentially supplies the touch panel scanning voltage (Vstc) to the counter electrode (Tx) of each block divided into m pieces.
The detection circuit (108) is configured to: (a) Current flowing through the plurality of detection electrodes (Rx) when the touch panel scanning voltage (Vstc) is supplied to the counter electrode (Tx) of each of the divided blocks. And (b) the (m + 1) th counter electrode (Txv) is detected with respect to the counter electrode (Tx) of each block divided into m blocks. It is assumed that there is a touch panel scanning voltage (Vstc) supplied to the counter electrode (Tx) of each block divided into m with respect to the (m + 1) th counter electrode (Txv). Assuming that a synchronized touch panel scanning voltage (Vstc) has been supplied, it is determined whether it is noise or a water droplet based on the current flowing through the plurality of detection electrodes (Rx).
(2) When the detection circuit (108) determines that it is a water droplet in (b), the detection circuit (108) performs a water droplet process (S230) to perform a touch determination (S202).
The water droplet process (S230) is a process (S232) for averaging the data around the touch intersection.
The detection circuit (108) performs the touch determination (S202) based on the first threshold value.
(3) When the detection circuit (108) determines that it is noise in (b), the detection circuit (108) performs a noise process (S220) to perform a touch determination (S202).
The noise process (S220) is a process (S222) for calculating an average value in a plurality of frames.
The detection circuit (108) makes a touch determination (S202) based on the second threshold value.
(4) When the detection circuit (108) determines that there are no noise and water droplets in (a), the touch determination (S202) is performed based on the third threshold value.
(5) The detection circuit (108) includes a plurality of integration circuits (10) provided for each of the plurality of detection electrodes (Rx), and an AD converter (converter) that converts output voltages of the plurality of integration circuits (10) into digital data. 12).
Each integrating circuit (10) is supplied with a touch panel scanning voltage (Vstc) to the counter electrode (Tx) of each block divided into m pieces, and when the fictitious (m + 1) th counter electrode (Txv) When an imaginary touch panel scanning voltage (Vstc) is supplied to the counter, the current flowing through each detection electrode (Rx) is divided into m counter electrodes (Tx) of each block and the imaginary (m + 1) Integration is performed for each counter electrode (Txv).
(6) In (a), a value closer to the least significant data than the intermediate value between the least significant data and the most significant data in the digital data that can be converted by the AD converter (12) is set as the first operating point. The value of the digital data when the integrated value for each counter electrode (Tx) of each block divided into m pieces of the plurality of integrating circuits (10) is converted by the AD converter (12) and the first operating point When the difference is smaller than the predetermined third threshold, it is determined that there is noise or water droplets.
(7) In (b), with the most significant data as the second operating point (A in FIG. 17), the integrated value of the imaginary (m + 1) th counter electrode (Txv) of the plurality of integrating circuits (10) The digital data value when the signal is converted by the AD converter (12) is a value between the second operating point (A in FIG. 17) and the least significant data, and the second operating point (in FIG. 17). When the difference from A) is larger than a predetermined fourth threshold value (C (Th) in FIG. 17), it is determined as noise.
(8) The digital data converted by the AD converter (12) is 10-bit data.
The first operating point has a value of 250 to 350 in decimal notation.
The second operating point (A in FIG. 17) is a value close to 1023 in decimal.
(9) When it is determined as a water droplet in (b) above, the detection circuit (108) is an electrode (T1, T2, T3, T4) in which the digital data converted by the AD converter (12) shows a maximum value. The digital data converted by the AD converter (12) corresponding to the peripheral electrodes (AR1, AR2, AR3, AR4) and the local maximum value are averaged, and the averaged data value is the first operation. When the difference between the point and the maximum value and the difference from the first operating point is larger than a predetermined fifth threshold, it is determined that there is a touch, and the rest is determined that there is no touch. .
The peripheral electrodes (AR1, AR2, AR3, AR4) are eight electrodes adjacent to the electrode showing the maximum value, and the average is obtained as an arithmetic average of nine digital data.
(10) When it is determined as noise in (b) above, the detection circuit (198) causes the integration circuit (10) corresponding to the detection electrode (Rx) where the noise is detected to be divided into m pieces. Digital data when the integrated value for each counter electrode (Tx) of the block is converted by the AD converter (12) is passed through the averaging filter, and the data value in the data after passing through the averaging filter is: The one having the maximum value (A in FIG. 18) is determined as an actual touch electrode, and the data value is a value between the maximum value (A in FIG. 18) and the least significant data, and the maximum value (FIG. 18). An electrode having a difference from 18) A) larger than a predetermined sixth threshold (Th1) is identified as an aerial touch electrode.
The averaging filter calculates an arithmetic average of digital data for 20 frames.

As described above, according to the present embodiment, it is possible to distinguish between external noise and water droplet adhesion with a simple algorithm (software). As a result, touch report delay can be reduced. In addition, erroneous touch reports due to water droplets can be prevented.
In this embodiment, the “touch panel drive frequency is freely adjusted” in the above-described in-cell liquid crystal display device which is the premise of the present invention and the in-cell liquid crystal display device which is the premise of the present invention. By combining with the “Yes” technology, the influence of noise can be reduced, but this embodiment can also be applied to a general in-cell type liquid crystal display device.

  For convenience of explanation, the number of scanning electrodes (counter electrodes) and detection electrodes shown in the drawings differs depending on the drawings. However, m scanning electrodes (m is an integer of 2 or more) and n detection electrodes (n is an integer of 2 or more) are sufficient.

2 First substrate 3 Second substrate 4 Liquid crystal composition 5 Liquid crystal driver IC
DESCRIPTION OF SYMBOLS 10 Integration circuit 11 Sample hold circuit 12 AD converter 13 Memory (RAM)
21 counter electrode 22 counter electrode signal line 25 drive circuit input terminal 31 detection electrode 33 dummy electrode 36 detection electrode terminal 40 front window (or protective film)
53 Flexible Wiring Board for Connection 101 LCD Driver 102 Sequencer 103 Touch Panel Scan Voltage Generation Circuit 104 Delay Circuit 106 Decoder Circuit 107 Touch Panel 108 Detection Circuit 1051, 1052 Register 200 Pixel Part 201 Water Drop 502 Finger MFPC Main Flexible Wiring Board Tx Touch Panel Scan Electrode Rx Touch panel detection electrode

Claims (20)

The display device
A first substrate having a pixel electrode and a counter electrode;
A second substrate having a plurality of detection electrodes of the touch panel;
A liquid crystal sandwiched between the first substrate and the second substrate;
A driving circuit for supplying a counter voltage and a touch panel scanning voltage to the counter electrode;
A detection circuit that detects the presence or absence of a touch based on currents flowing through the plurality of detection electrodes;
When m is an integer of 2 or more (m ≧ 2), the counter electrode is divided into m blocks,
The counter electrode of each block divided into m is provided in common for each pixel of a plurality of continuous display lines,
The counter electrode of each block divided into m pieces also serves as a scanning electrode of the touch panel,
The driving circuit sequentially supplies a touch panel scanning voltage to the counter electrode of each block divided into m pieces,
The detection circuit includes:
(A) When a touch panel scanning voltage is supplied to the counter electrode of each of the m divided blocks, the presence or absence of noise or water droplets is detected based on the current flowing through the plurality of detection electrodes. And
(B) It is assumed that the (m + 1) -th counter electrode exists for the counter electrode of each of the m divided blocks, and the m-th counter electrode has the m Assuming that the touch panel scanning voltage synchronized with the touch panel scanning voltage supplied to the counter electrode of each divided block is supplied, based on the current flowing through the plurality of detection electrodes, noise and water droplets It is determined whether it is any. The display device according to claim 1.
When the detection circuit determines that it is a water droplet in (b), the detection circuit performs a water droplet process to perform touch determination. The display device according to claim 2.
The water droplet process is a process of averaging data around the touch intersection. The display device according to claim 3.
The detection circuit performs the touch determination based on a first threshold value. The display device according to claim 1.
When the detection circuit determines that noise is detected in (b), the detection circuit performs noise processing to perform touch determination. The display device according to claim 5, wherein
The noise processing is processing for calculating an average value in a plurality of frames. The display device according to claim 6.
The detection circuit performs the touch determination based on a second threshold value. The display device according to claim 1.
When it is determined in (a) that there is no noise and no water droplet, the detection circuit performs a touch determination based on a third threshold value. The display device according to claim 1.
The detection circuit includes:
A plurality of integration circuits provided for each of the plurality of detection electrodes;
An AD converter for converting output voltages of the plurality of integration circuits into digital data;
Have
Each integration circuit is supplied with a touch panel scanning voltage when the touch panel scanning voltage is supplied to the counter electrode of each of the m divided blocks, and when the imaginary (m + 1) th counter electrode is supplied. The current flowing through each detection electrode is integrated for each of the m counter electrodes divided into the m blocks and the imaginary (m + 1) th counter electrode,
In (a), the plurality of integrating circuits in the digital data that can be converted by the AD converter, with a value closer to the least significant data as a first operating point than an intermediate value between the least significant data and the most significant data. The difference between the digital data value and the first operating point when the integrated value for each counter electrode of each block divided into m is converted by the AD converter is smaller than a predetermined third threshold value. In case it is judged that there is noise or water drops,
In (b), the most significant data is the second operating point, and the digital data when the integrated value of the imaginary (m + 1) th counter electrode of the plurality of integrating circuits is converted by the AD converter is used. When the value is a value between the second operating point and the least significant data and the difference from the second operating point is larger than a predetermined fourth threshold, it is determined as noise. The The display device according to claim 9.
The digital data converted by the AD converter is 10-bit data,
The first operating point is a decimal value between 250 and 350;
The second operating point is a value close to 1023 in decimal. The display device according to claim 9.
When it is determined as a water droplet in (b), the detection circuit converts the digital data converted by the AD converter into a digital signal converted by the AD converter corresponding to an electrode around the electrode showing the maximum value. The data and the local maximum value are averaged, the averaged data value is a value between the first operating point and the local maximum value, and the difference between the first operating point is a predetermined fifth value. If the threshold value is larger than the threshold value, it is determined that there is a touch and the other case is that there is no touch. The display device according to claim 11.
The peripheral electrodes are eight electrodes adjacent to the electrode showing the maximum value, and the average is obtained as an arithmetic average of nine digital data. The display device according to claim 9.
When it is determined as noise in (b), the detection circuit uses the integration value for each counter electrode of each block divided into the m blocks in the integration circuit corresponding to the detection electrode in which noise is detected. The digital data when converted by the AD converter is passed through an averaging filter, and the data after passing through the averaging filter is determined as an actual touch electrode if the data value has the maximum value. An electrode whose value is a value between the maximum value and the least significant data and whose difference from the maximum value is larger than a predetermined sixth threshold is identified as an imaginary touch electrode. The display device according to claim 13,
The averaging filter calculates an arithmetic average of digital data for 20 frames. The display device
A first substrate having a pixel electrode and a counter electrode;
A second substrate having a plurality of detection electrodes of the touch panel;
A liquid crystal sandwiched between the first substrate and the second substrate;
A driving circuit for supplying a counter voltage and a touch panel scanning voltage;
A detection circuit that detects the presence or absence of a touch based on currents flowing through the plurality of detection electrodes;
With
When m is an integer of 2 or more (m ≧ 2), the counter electrode is divided into m blocks,
The counter electrode of each block divided into m is provided in common for each pixel of a plurality of continuous display lines,
The counter electrode of each block divided into m pieces also serves as the scanning electrode of the touch panel,
The driving circuit sequentially supplies a touch panel scanning voltage to the counter electrode of each block divided into m pieces,
The detection circuit includes:
(A) When a touch panel scanning voltage is supplied to the counter electrode of each of the m divided blocks, the presence or absence of noise or water droplets is detected based on the current flowing through the plurality of detection electrodes. And
(B) It is assumed that the (m + 1) -th counter electrode exists for the counter electrode of each of the m divided blocks, and the m-th counter electrode has the m Assuming that the touch panel scanning voltage synchronized with the touch panel scanning voltage supplied to the counter electrode of each divided block is supplied, based on the current flowing through the plurality of detection electrodes, noise and water droplets Is to detect which one is
(C) When it is determined to be a water droplet in (b) above, a water droplet process is performed to perform touch determination based on the first threshold,
(D) When it is determined that noise is detected in (b), noise processing is performed to perform touch determination based on the second threshold,
(E) When it is determined in (a) that there is no noise and no water droplets, touch determination is performed based on the third threshold value. The display device of claim 15,
The water droplet process is a process of averaging data around the touch intersection. The display device of claim 15,
The noise processing is processing for calculating an average value in a plurality of frames. The display device of claim 15,
The detection circuit includes:
A plurality of integration circuits provided for each of the plurality of detection electrodes;
An AD converter for converting output voltages of the plurality of integration circuits into digital data;
Have
Each integration circuit is supplied with a touch panel scanning voltage when the touch panel scanning voltage is supplied to the counter electrode of each of the m divided blocks, and when the imaginary (m + 1) th counter electrode is supplied. Then, the current flowing through each detection electrode is integrated for each of the m counter electrodes divided into the m blocks and the imaginary (m + 1) th counter electrode. The display device of claim 18,
In (a), in the digital data that can be converted by the AD converter, a value closer to the lower limit than the lowest intermediate data and the highest intermediate value is a first operating point, and the integration circuits When the difference between the digital data value obtained by converting the integral value for each counter electrode of each block divided into m pieces by the AD converter and the first operating point is smaller than a predetermined third threshold value. It is determined that there is noise or water droplets. The display device of claim 18,
In (b), the most significant data is the second operating point, and the digital data when the integrated value of the imaginary (m + 1) th counter electrode of the plurality of integrating circuits is converted by the AD converter is used. When the value is a value between the second operating point and the least significant data and the difference from the second operating point is larger than a predetermined fourth threshold, it is determined as noise. The

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